dlib C++ Library - surf_ex.cpp

// The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt
/*
 This is a simple example illustrating the use of the get_surf_points() function. It
 pulls out SURF points from an input image and displays them on the screen as an overlay
 on the image.
 For a description of the SURF algorithm you should consult the following papers:
 This is the original paper which introduced the algorithm:
 SURF: Speeded Up Robust Features
 By Herbert Bay, Tinne Tuytelaars, and Luc Van Gool
 This paper provides a nice detailed overview of how the algorithm works:
 Notes on the OpenSURF Library by Christopher Evans
*/
#include <dlib/image_keypoint/draw_surf_points.h>
#include <dlib/image_io.h>
#include <dlib/image_keypoint.h>
#include <fstream>
using namespace std;
using namespace dlib;
// ----------------------------------------------------------------------------
int main(int argc, char** argv)
{
 try
 {
 // make sure the user entered an argument to this program
 if (argc != 2)
 {
 cout << "error, you have to enter a BMP file as an argument to this program" << endl;
 return 1;
 }
 // Here we declare an image object that can store rgb_pixels. Note that in dlib
 // there is no explicit image object, just a 2D array and various pixel types. 
 array2d<rgb_pixel> img;
 // Now load the image file into our image. If something is wrong then load_image()
 // will throw an exception. Also, if you linked with libpng and libjpeg then
 // load_image() can load PNG and JPEG files in addition to BMP files. 
 load_image(img, argv[1]);
 // Get SURF points from the image. Note that get_surf_points() has some optional
 // arguments that allow you to control the number of points you get back. Here we
 // simply take the default.
 std::vector<surf_point> sp = get_surf_points(img);
 cout << "number of SURF points found: "<< sp.size() << endl;
 if (sp.size() > 0)
 {
 // A surf_point object contains a lot of information describing each point.
 // The most important fields are shown below:
 cout << "center of first SURF point: "<< sp[0].p.center << endl;
 cout << "pyramid scale: " << sp[0].p.scale << endl;
 cout << "SURF descriptor: \n" << sp[0].des << endl;
 }
 // Create a window to display the input image and the SURF points. (Note that
 // you can zoom into the window by holding CTRL and scrolling the mouse wheel)
 image_window my_window(img);
 draw_surf_points(my_window, sp);
 // wait until the user closes the window before we let the program 
 // terminate.
 my_window.wait_until_closed();
 }
 catch (exception& e)
 {
 cout << "exception thrown: " << e.what() << endl;
 }
}
// ----------------------------------------------------------------------------